Test-DscDnsParameterState: Move enhancements to Test-DscParameterState in module DscResource.Common

[johlju]

The function Test-DscDnsParameterState is enhanced with additional parameters compared to the function Test-DscParameterState that is available in the module DscResource.Common.
These enhancements should be merged into the function in DscResource.Common so we can remove the duplicate code in this module.

This was discovered when converting this module to the new CI pipeline.

[gaelcolas]

Tagging @raandree on that one...

[johlju]

I tried to move this over to Test-DscParameterState in the module DscResource.Common, but the unit tests for xDnsServerRootHint fail - Test-DscParameterState returns true even if should return false. It looks like something is going on in the reverse check because it works when removing the parameter ReverseCheck though in this instance that parameter is important.

After 3 hours of debugging I'm no closer to a solution - Test-DscParameterState works from command line when I try to reproduce the problem - or more correctly I don't find the correct repro case.

[johlju]

This test fails:

https://github.com/dsccommunity/xDnsServer/blob/9d4f3ef34f7e1d2722594462256b2c60f0578e05/tests/Unit/MSFT_xDnsServerRootHint.Tests.ps1#L111-L114

I changed this row to Test-DscParameterState but then it always return $true:

https://github.com/dsccommunity/xDnsServer/blob/9d4f3ef34f7e1d2722594462256b2c60f0578e05/source/DSCResources/MSFT_xDnsServerRootHint/MSFT_xDnsServerRootHint.psm1#L121

Actually if I add these two rows without the parameter ReverseCheck then the variable $resultReverse will be $true even if both $result and $resultReverse should be $false. Both compares against an empty hashtable that is passed in $currentState for the key NameServers.

$result = Test-DscParameterState -CurrentValues $currentState -DesiredValues $desiredState -TurnOffTypeChecking
$resultReverse = Test-DscParameterState -CurrentValues $desiredState -DesiredValues $currentState -TurnOffTypeChecking

[johlju]

The problem is Compare-DscParameterState. The closest I got to a repro case is the below code which does not return a hashtable but $null from Compare-DscParameterState.

 $nameServers = [Microsoft.Management.Infrastructure.CimInstance[]] @(
    New-CimInstance -ClassName 'MSFT_KeyValuePair' -Namespace 'root/microsoft/Windows/DesiredStateConfiguration' -Property @{
        Key   = 'B.ROOT-SERVERS.NET.'
        Value = '199.9.14.201'
    } -ClientOnly

    New-CimInstance -ClassName 'MSFT_KeyValuePair' -Namespace 'root/microsoft/Windows/DesiredStateConfiguration' -Property @{
        Key   = 'M.ROOT-SERVERS.NET.'
        Value = '202.12.27.33'
    } -ClientOnly
 )

Compare-DscParameterState -CurrentValues @{
    IsSingleInstance = 'Yes'
    NameServer = @()
} -DesiredValues @{
    NameServers = $nameServers
    IsSingleInstance = 'Yes'
    Verbose = $true
} -TurnOffTypeChecking -ReverseCheck

[johlju]

Submitted a bug in issue dsccommunity/DscResource.Common#65